blk-lib: don't check bdev_get_queue() NULL check

Based on the comment present in the bdev_get_queue()
bdev->bd_queue can never be NULL. Remove the NULL check for the local
variable q that is set from bdev_get_queue() for discard, write_same,
and write_zeroes.

Signed-off-by: Chaitanya Kulkarni <kch@nvidia.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20220215115247.11717-2-kch@nvidia.com


Signed-off-by: Jens Axboe <axboe@kernel.dk>